In the Old Testament, there is a mysterious figure known as the Angel of the LORD. What is mysterious about the Angel of the LORD is the identity of this figure. In one way, this being seems to be an angel. In another way, this being is so important that he seems to speak with God’s words. It looks almost like the Angel of the LORD is God with some sort of visible (but not a fleshly) body.
This has led some theologians to see the Angel of the LORD as a christophany rather than a theophany. That is, they see the Angel of the LORD as a pre-incarnation appearance of the Son of God (it would be an anachronism to call him Jesus despite what I do in the title).
I am very skeptical of this theory. It is not that it is impossible, although Hebrews goes out of the way to differentiate Jesus from angels (see my The Watchtower and the Word).
My question is more about why someone would make this identification in the first place. It seems as if people are asking, what person of the Trinity has a body which could appear as the Angel of the LORD? The answer seems to be Jesus. The assumption was that pre-incarnation Jesus was just spirit but it was spirit shaped like a human body that could fit perfectly into his Jesus body.
There is no reason to believe this. God the Son should be no different than God the Father or God the Spirit. The Angel of the LORD could just as easily have been the Father or the Spirit as the Son.
So what or who was the Angel of the LORD? My guess is that the Angel of the LORD was in fact an angel. This angel had special authority to speak the words of God. If God could speak through a burning bush, there is no reason why he could not speak through an angel. This angel did not speak his own opinion but spoke directly from God.